This book is an excellent way to prepare for the LSAT, though the material it contains is not identical to the material Kaplan presents in its courses.
Cracking the LSAT : With Sample Tests on Cd-Rom
Princeton Review's LSAT text is concise and effective. If you are not taking a course in preparation for the test, it may make sense for you to purchase both this book and the Kaplan book for the variety of practice questions you will get.